/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.stdlib.text.operator;

import axil.api.AxilObject;
import axil.api.extend.Operator;
import axil.framework.type.Concatenated;

import static axil.framework.Functions.*;


/**
 * This operator is provided for compatibility with the syntax for Microsoft
 * Excel. The text concatenation (using the '&' symbol) is rather odd, but we
 * want the novice script writer to feel as comfortable as possible.
 */
public class Concatenate implements Operator {
	/**
	 * Execute this operator with the given operands. The given operands have
	 * already been evaluated. If this operation does not make sense for the
	 * given operands, then an exception is thrown.
	 *
	 * @param left
	 * 	The left operand, which can be any Axil object. The value given is
	 * 	never null but may be the nil object (Axil.NIL).
	 *
	 * @param right
	 * 	The left operand, which can be any Axil object. The value given is
	 * 	never null but may be the nil object (Axil.NIL).
	 *
	 * @return
	 * 	Returns any Axil object, but not null.
	 */
	public AxilObject eval(AxilObject left, AxilObject right) {
		if (left instanceof Concatenated) {
			return ((Concatenated)left).concatenate(right);
		}
		throw error(axil(), "invalid-operand",
			  nv("operator", "&"), nv("type", left.type()));
	}
}
